Armature retaining assembly for an electromagnetic relay



March 15, 1960 a. A. WALLACE ETAL 2,929,001

ARMATURE RETAINING ASSEMBLY FOR AN ELECTROMAGNETIC RELAY Filed June 13,1957 FIG. I

United States Patent ARMATURE RETAINING ASSEMBLY FOR AN ELECTROMAGNETICRELAY Bert A. Wallace, Chicago, BL, and Earl Van Wie, Las Vegas, Nev.,asignors to International Telephone and Telegraph Corporation, New York,N.Y., a corporation of Maryland Application June 13, 1957, Serial No.665,394

2 Claims. (Cl. 317-176) This invention relates to an armature retainingassembly for an electromagnetic relay, particularly of the bellcranktype used in telephone switchboards, with the armature fulcrumed on theforward end of the magnetic return plate. Its principal object is toprovide a new and improved armature retaining assembly which providesease of adjustment in aligning the electromagnet armature in its desiredoperating position and in maintaining the armature in its operatingposition irrespective of any precise location of the armature retainingassembly.

In the known relay construction of the above type, a generally T-shapedarmature retainer is employed. The main portion passes through a slot inthe armature and is secured to the magnetic return plate, thus servingto limit movement of the armature along the fulcrum line. Movement ofthe armature away from the fulcrum line, which may tend to occur whenthe electromagnet is deenergized, is limited by the head portion of theretainer. Difliculty, however, is often encountered in properlyadjusting the retainer and in aligning the head portion with thearmature to serve its retaining purpose without mechanical bind.

According to the invention, the foregoing difficulty is avoided byproviding a spring member which urges the armature toward the fulcrumline, and which has a sufficiently small spring rate that accuratepositioning of the spring member is not required.

In its illustrated form, the retaining spring member is convenientlysecured to the usual T-shaped armature retainer which has its headportion located beyond the extremities of the return plate to permitonly the spring member to engage the armature to'hold it against itsfulcrum line. Friction between the armature and the arms of the springmember is negligible because of the small area of contact and of thesmall amount of the spring force.

The above-mentioned and other features and objects of this invention andthe manner of obtaining them will become more apparent, and theinvention will be best understood, by reference to the followingdescription of the invention taken in conjunction with the accompanyingdrawings comprising Figs. 1 to 4, wherein:

Fig. l is a plan view of a relay embodying the invention;

Fig. 2 is a side elevation view of the relay of Fig. l; Fig. 3 is afront elevation view of the relay of Fig. 1; and

Big. 4 shows the armature-retaining assembly of the relay of Fig. lgreatly enlarged.

Referring particularly to Figs. 1 and 2, the relay shown thereinincludes an electromagnet 10, an armature 11, a twin stack switchassembly 12, both stacks of which are actuable by the electromagnetthrough the armature, and an L-shaped return plate 13 on which theswitch assembly and armature are mounted.

The electromagnet includes a coil 14 and a cylindrical magnetic core 16extending therethrough. The

2,929,001 Patented Mar. 15, 1960 ICC rear end of core 16 is drilled andtapped to receive screw 17 to secure to coil to the return plate 13.

The electromagnet 10 has a round front spoolhead 18 and a square rearspoolhead 19. The front and rear spoolheads are secured to the core 16,as by press fit.

Coil 14 has rearwardly extending winding terminals 20, located in a rowalong the lower edge of the rear spoolhead 19.

As shown most clearly in enlarged Fig. 4, the armature is held inposition at the front of return plate 13 by an armature-retainingassembly comprising a retainer member 23 and a spring member 78.

The retainer member 23 is generally of T-shaped structure having a flatbifurcated shank portion 28 and crossarms 24 disposed at right angleswith portion 28. To enable the retainer member 23 and armature to bemounted on the return plate, an aperture or cut-out portion is providedin the arm 26 of armature 11 through which the flat bifurcated extendingportion 28 of the retainer may be fastened to the return plate 13. Thebifurcated extension portion comprises a pair of arms 29 defining a slotwithin which a fastening screw 30 is snugly accommodated for threadedengagement with a hole in the top of the return plate 13. In thismanner, the arms 29 can be either tightened against the return plate orslidably disengaged from the return plate upon loosening the screw 30.Member 23 abuts the sides of the aper ture of armature 11 to prevent anyside movement thereof.

Spring member 78, made from spring-tempered wire, is formed to besecured snugly to the crossarms 24 of armature retainer 23 by a clip-onaction. When secured to retainer 23, the straight portion (Fig. 3) ofspring member 78 underlies portion 28 of retainer 23 to prevent anyrotation of the spring member and the two arms 79 of member 78, loopedaround respective crossarm portions 24, extend upwardly in a planemaking approximately a 30-degree angle with the plane of the retainer23, the arms being disposed between the crossarms 24 and the bifurcatedend of the retainer.

When the retainer 23, with its spring member 78 secured thereto, ismounted on plate 13 by screw 30, the bifurcated portion 28 of retainer23 is longitudinally positioned by sliding it rearwardly until thespring arms 79 come into contact with armature 11 and are disposed atabout equal angles with parts 26 and 27, which comprise the angularlydisposed arms of the bell-crank armature 11. In this position, the arms79 bear against the bent portion of armature 11 to prevent its upward orforward displacement.

The above arrangement provides ease in adjusting the armature-retainingassembly since the yield of the spring arms 79 permits satisfactoryarmature 27 operation irrespective of any precise location of thearmature retainer 23. on return plate 13.

The twin-stack switch assembly of Figs. 1 and 2 includes a cap-plate 37,base plate 38, and parts clamped between them by screws 40 which passthrough openings in the cap-plate and intervening parts to the baseplate, wherein they are threadedly received. Two opposed columns 42 and43 of the contact sets are included in the same unitary assembly 12.This construction enhances rigidity and reduces the number of assemblyand clamping screws required. The switch assembly is readily installedin position on return plate 13 and is simply secured by two mountingscrews 41 which pass through assembly 12 for threaded engagement withapertures (not shown) in the upper surface of return plate 13. Theswitch assembly lies fiat upon the return plate with protruding ends ofclamping screws 40 thereof being received in provided clearance openings(not shown) in the return plate.

The traveling blades of both columns are moved by a pair of similaractuating ladders 58, as shown in Figs. 1 and 2, which move the bladesinto and out of electrical contact with the fixed blades of theirrespective contact sets in response to movement of the associatedarmature. The ladder provided for column 42 is actuated simultaneouslywith the ladder of column 43 by the armature 11. Each of the contactblades of columns 42 and 43 has a terminal portion 60 for the attachmentof circuit wires. The terminals are staggered as shown in Fig. 1 forwiring convenience.

Upon energization of the electromagnet 10, the associated armature 11turns about its axis to bring its lower portion 27 into contact with theend of the core 16 and to move its upper portion 26 to cause thetravelling blades of columns 42 and 43 to move into contact with theirrespective stationary blades. During such movement of the armature 11,lines of magnetic flux maintain the armature against the knife-like edgeof return plate 13, the arms 79 of spring assembly 78 permitting freemovement of the armature about its fulcrum.

Upon deenergization of the electromagnet, the downward tension of theassociated traveling blades of the switch assembly serves to return thearmature to its normal illustrated position. While returning to itsunoperated position as a result of discontinuation of magnetic fiux, thearmature has a tendency to move away from the fulcrum line and be out ofoperating position when the electromagnet is energized again. However,according to the invention arms 79 by spring tension maintain thearmature properly in position against the return plate pivot edge.

While we have described above the principles of our invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of our invention.

We claim:

1. An electromagnetic device comprising an electromagnet, a magneticplate secured to the electromagnet, and an armature pivotally supportedon an elongated fulcrum on the plate, the armature having an aperturethrough which the plate is made accessible, means including a rigidretaining member and a spring retaining member for maintaining thearmature on the fulcrum in operative relation with the electromagnet formovement about the fulcrum between an operated and an unoperatedposition, means for securing the rigid retaining member to the platethrough the aperture in the armature to limit the movement of thearmature along the fulcrum, means for securing the spring retainingmember fixed on the rigid retaining member for resilient engagement withthe armature to hold the armature against movement away from thefulcrum, and adjustment means for variably tensioning the springretaining member against the armature to urge it variably against thesaid fulcrum, said adjustment means being included in the said means forsecuring the retaining member to the said plate and comprising means foradjustably positioning the retaining member on the said plate.

2. Structure for yieldingly retaining an apertured armature of anelectromagnet operatively in position on a fulcrum fixed with theelectromagnet, which comprises a T-shaped rigid retaining member havingits stem portion extending through the aperture of the armature andremovably fixed with the electromagnet structure, with the head portionwider than the aperture in the armature and located along the fulcrumbut spaced outwardly therefrom in a position to clear the armature, anda resilient supplemental retaining member attached to the head end ofthe rigid retaining member to yieldingly hold the armature on itsfulcrum, the supplemental retaining member consisting of a single lengthof spring wire of a generally U-shaped form which provides a pair ofarmature-engaging arms each extending transversely of the fulcrum linebetween the armature and the head portion of the rigid member, such armsbeing joined integrally by a common portion which crosses and contactsthe stem portion of the rigid member near the head portion thereof,eachtarrn of the resilient supplemental member including an intermediateportion which extends around a separate arm of the head portion of therigid retaining member, thereby providing an increased spring-armlength.

References Cited in the file of this patent UNITED STATES PATENTS2,235,861 Wood Mat. 25, 1941 2,461,360 Vincent Feb. 8, 1949 2,686,850Earle Aug. 17, 1954

